A microprocessor-based real time data acquisition system for study of acoustically excited flow fields
Year: 1980
Type: conference-abstract
Abstract: The data-acquisition chain described in this paper allows mapping out the structure of flows generated by the interactions of high intensity sound with boundary layers in high-speed flow, specifically, the nearfield over the orifice of a Helmholtz resonator in grazing flow. Some of the stringent requirements which had to be met were: (a) local measurement at approximately 600 locations of the instantaneous vector velocity in four quadrants, accurately phased to the excitation; (b) signal recovery from the noise level of the turbulent flow; (c) signal processing without approximation of the complex instrument transfer functions; (d) on line monitoring and correction for drift during the 15-h continuous run. The microcomputer “actively” participates in the process. It generates the excitation, positions the probes, reads the outputs of two split-film CT anemometers and two microphones 64 times per cycle at 100 Hz, reduces them to velocity and angle data by look up in calibration tables stored in memory, conditionally averages data at constant phase over approximately 5000 cycles to reject uncorrelated turbulence and stores the results on magnetic disks. [This research was sponsored by NASA-Lewis Research Center.]
DOI: 10.1121/1.2004835
Authors: Bruce E. Walker, Andrew F. Charwat, Ronald H. Olch
Institution: University of California, Los Angeles
Language: English
Subfield: Aerospace Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2095348425